Metadoxine Induced Reproductive Damage and Mechanism in the Male Rats

Abstract: [Objective] MTDX (Metadoxine, MTDX) is a drug of metabolization-balance, which was first invented and produced in Italy in 1980s. Now it is widely used to treat hepatic disorders originating from acute and chronic alcoholism in abroad. MTDX is an ion-pair, that is neither a salt nor a mono-substance, but it encompasses some properties of salts and some of the covalent bonds-between pyridoxine (or Vitamin B5, i.e. PN) and pyrrolidone carboxylate. Vitamin B6includs PN, PL and PM, but generally refer to PN. We firstly found, in preclinical toxicology study, that MTDX caused reproductive damage in the male rats. At present, a phase II clinical study of MTDX has been carried out in china, and it may be used to treat alcoholic liver disease. The purpose of the present study was to confirm its reproductive toxicity and to explore the possible mechanisms in order to provide more safety information for doctors and SFDA.[ Methods ] We researched the reproductive toxicity and possible mechanism of MTDX with 3 in vivo and 2 in vitro experiments. They are as follows: 1) To confirm the male reproductive toxicity and the external and inner toxic dose. Male Wistar rats were administered daily by oral gavage of 0, 250, 500, 1000 mg/kg of MTDX for 4 weeks. The organ coefficients, sperm quality and the serum testosterone level were determined. The tissure contents of B6 vitamers (i.e. PN, PL and PM) in liver and testis in the male wistar rats were also mesred by reversed-phase ion-pair chromatographic method. 2) The find out the active toxic components of MTDX, which caused reproductive damage in the male rats. Male Sprague-Dawley rats were administered daily by oral gavage of 0, 250, 500,1000 mg/kg of MTDX, and of a single dose of VitB6(567 mg/kg), L-PCA(433 mg/kg), and L-PCA (433 mg/kg) + VitB6 (567 mg/kg), respectively for 4 weeks. The organ coefficient and histopathological changes of sexual glands, sperm quality and the level of serum testosterone were determined. 3) Hershberger assay was used to observe the antiandrogenic effect of MTDX and its components. Sixty male Sprague-Dawley rats of 4 weeks age were be castrated. After 2 weeks, the other groups rats were dosedonce a day for 7 days with testosterone propionate (1 mg/kg, sc) plus gavage dosed of either distilled water vehicle or MTDX (400 mg/kg, 1200 mg/kg) or VitB6 (225 mg/kg, 700 mg/kg) or L-PCA (175 mg/kg, 500 mg/kg) or VitB6 + L-PCA(225 mg/kg + 175 mg/kg, 700 mg/kg + 500 mg/kg) , but one group castrated rats were subcutaneously injected with peanut oil and gavaged with distilled water as the control. Then, the liver, kidney, adrenals, prostate, glans penis, seminal vesicle levator ani and bulbocavernosus muscles were removed and weighed. The two vitro ways are: 1) Observed the effects of MTDX and PN at different concentrations (0, 0.1, 1, 10, and 100 mmol) on T production by miced-testis in vitro, by the approaches of tissue culture and radioactivity. 2) 21-day male SD rats were euthanized by asphyxiation, and the testes were digested with trypsin and collagenase, and filtered with 80- m mesh. The cultures were maintained in humidified atmosphere (95% air/5% CCh). The media (serum-free) were changed every other day, and the Sertoli cells were expose to MTDX and PN (0, 0.1,0.5, 5, and 50 mmol) on the third day for 24 h. hen the media were collected respectively for detection of lactate level.[Results] The in vivo studies:!) After 4 weeks administration, the relative weights of testes, epididymis, prostate gland and seminal vesicle decreased remarkably in a dose-dependent manner, and the 4 weeks treatments also caused decreased spermatid count in the epididymis cauda, sperm motility and increased sperm malformation rate. In addition, serum testosterone concentration significantly increased, compared with control group in the 1000 mg/kg MTDX group. The total VitB6, PL, PM and PN level in the testes in 1000 mg/kg MTDX group increased significantly compared with those in the middle, and low dose groups as wel as the control group. In the 500 mg/kg MTDX grou…
Key words: metadoxine; vitaminB_6; pyrrolidone carboxylate; Sertoli cells culture; male reproductive toxicity; antiandrogen; Hershberger assay; testis; HPLC; lactate